The present invention relates to mobile communication in general, and in particular to the wideband code division multiple access (CDMA) mobile equipment capable of transmitting bi-directional real-time multichannel sound.
Sound can usually be divided into single-channel or multi-channel sound, and further into narrowband or wideband sound by virtue of sound bandwidth. Common amplitude modulation (AM) broadcasting and wire-telephone fall into single-channel sound with bandwidth less than 4 KHz and poorer sound quality; frequency modulation (FM) stereo broadcasting pertains to multichannel sound with bandwidth about 15 KHz and better sound quality.
Generally speaking, broadcasting and television are also part of mobile communication system when they are in a mobile status. FM broadcasting system and mobile station can only, however, receive stereo or multichannel music and voice. They can not carry out bi-directional voice or character information transmission, therefore they are not the mobile communication system in common sense. On the other hand, although such the mobile communication systems mainly for exchanging information, as cellular mobile telephone, radio pager and satellite mobile communication etc. can provide bi-directional voice and character information exchange or transmission, they cannot provide music or multichannel sound service of high quality.
The mobile communication system has evolved from the first generation (1G) of mobile analog cellular system to the second generation (2G) of mobile digital cellular system. Based on the core technologies of analog modulation and frequency division multiple access (FDMA), the 1G mobile communication system used to transmit analog voice. While, based on the core technologies of digital transmission and time division multiple access (TDMA), the 2G mobile communication system is capable of transmitting encoded digital voice. Whether 1G or 2G system is, however, restricted by the transmission technology and capacity of subscriber. In order to transmit more voice within the restricted bandwidth the quality of analog or digital voice had to be degraded, so that neither of them could transmit high quality of sound, to say nothing of the transmission of multichannel music and voice. As far as the present applicant knows, there has not been so far any bi-directional communication equipment that can provide multichannel sound simultaneously in a mobile device.
CDMA digital cellular mobile communications system can, with large system capacity only restricted by interference, other than the bandwidth-restricted capacity of FDMA and TDMA, better realize the broadband data transmission. It can be the basis of providing bi-directional, high purity and high quality of multichannel sound service on the digital mobile communication system.
The present invention provides wideband CDMA mobile equipment capable of transmitting multichannel sound, so that the existing mobile communication system can, at the same time of information exchange, transmit high quality of sound. The user can not only obtain the demanded information, but also enjoy the music and voice service of high purity and quality from the mobile communication system.
The present invention further actualizes real-time bi-directional multichannel sound and image communication in combination of image encoding.
The wideband CDMA mobile equipment capable of transmitting multichannel sound according to the present invention, comprises sending unit, receiving unit, central processing unit (CPU) connecting with the said sending and receiving unit, duplexer connecting with the said sending and receiving unit, and antenna connecting with the said duplexer; wherein:
The said sending unit includes at least pickup sets, sound signal pre-processing sets, sound signal encoder, channel encoder, wideband CDMA modulator and radio-frequency (RF) sender; they are linked in a sequence; the output of the RF sender, connecting with the input of the duplexer, sends out to the antenna;
The said receiving unit includes at least RF receivers, wideband CDMA demodulator, channel decoder, sound signal decoder, sound signal post-processors and reproducer; they are linked in a sequence; the signal from antenna will be sent to the RF receiver via the duplexer;
The above pickup sets are composed of more than one pickup; the said sound signal pre-processing sets are composed of more than one sound signal pre-processor, with each sound signal pre-processor corresponding to one pickup; the said sound signal post-processing sets are composed of more than one sound signal post-processor.
According to the above technical scheme, the said sending unit includes further pick-up heads, image signal pre-processing unit and image signal encoder. They are linked in a sequence. The output of the image signal encoder is connected with input of the said channel encoder. The said receiving unit includes further image signal decoder, image signal post-processing unit and monitor. They are also linked in a sequence. The input of the image decoder is connected with the output of the channel decoder.
There are two or more than two of the said pickups that may be general or Hi-Fi pickup, or linked to sound source device by the line-in interface of multichannel sound.
The said sound reproducers is speaker sets or multichannel earphones, or can be linked out to other playing device by the line-out interface of multichannel sound.
The said sound signal encoder may be the sound signal encoder MP3 based on MPEG standard or the digital encoder in a CD player, or even AC-3 algorithm.
The said wideband CDMA modulator is a modulator with BPSK or QPSK spread spectrum mode keeping in line with the spread spectrum mode of the RF sender.
The said wideband CDMA demodulator is a demodulator with correlation operation as de-spreading spectrum mode and enhancing signal by RAKE receiver mode.
The said duplexer has two modes, i.e. frequency division duplex (FDD) and time division duplex (TDD). In the case of TDD mode, the said duplexer is connected with the CPU controlling the on-off of receiving and sending.
The said CPU includes central processor and attaching circuits containing man-machine interface circuit. The attaching circuits include at least large-scale memory unit capable of storing the received multichannel sound data.
The mobile equipment, according to the present invention, can access the system as terminal equipment of the mobile communication system in forms of portable machine, handset or vehicle machine.
In the sending unit of the mobile equipment, according to the present invention, the pickup sets or multichannel input device can produce electrical signal of multichannel sound. Signals from each sound source are multichannel-preprocessed respectively, including A/D transformation, via each channel, and then sent to the multichannel sound signal encoder. The signal encoder outputs digital code stream continuously or by frame, which will be sent to the channel encoder to increase capability of anti-interferences. The data output from the channel encoder will then be emitted after being modulated by wideband CDMA modulator to the specified radio communication band. In the receiving unit, the received radio signals are demodulated with wideband CDMA to restore the data stream containing sound signal. The data stream is, through the channel decoder and the sound signal decoder, sent to the sound signal post-processor, and then high quality of sound will be restored by speaker or multichannel earphone.
On account of the wideband CDMA digital transmission technology adopted in the mobile equipment of the present invention, under the precondition of ensuring transmission quality of bi-directional voice and character as well as capacity of subscribers, sufficient transmission bandwidth can be provided to support the bandwidth requirement of transmitting bi-channel music or voice. The mobile equipment of the present invention utilizes the high quality of voice encoding technology to support as FM and CD music or voice services. The mobile equipment of the present invention further utilizes multichannel earphone or speaker to restore multichannel sound. It also has optional multichannel output interfaces.
Owing to the multichannel source encoding and wideband CDMA transmission technology adopted in the present invention, it can provide high quality of multichannel e.g. stereo voice or music, and enjoyable sound service on the mobile equipment of the mobile communication system. In combination with the image encoding technology, a real-time bi-directional multichannel sound and image communication can be realized at the same time.